桥面纵坡对小半径曲线桥铺装层受力的影响分析

Influence of Longitudinal Slope of Bridge Deck on Stress of Pavement of Small Radius Curved Bridge

针对小半径曲线桥桥面沥青铺装层力学行为受路线纵坡大小影响的情况,文中以大温差地区某超高曲线桥为例,考虑沥青铺装层的黏弹性性质,分别计算温度、动荷载、温-荷耦合等不同荷载工况下的受力情况,分析不同工况下纵坡(4.22%,5.22%,6.22%,7.22%)对桥面铺装层受力的影响。结果表明,仅温度场或动荷载单独作用,铺装表层更容易产生受拉破坏,且不同纵坡对σ影响显著;动荷载单独作用或温-荷耦合作用,对铺装下层抗剪能力有更高要求;特别地,在温-荷耦合作用时,随纵坡增加,铺装表层应力总体呈现增大趋势,而对于铺装下层,当纵坡>6.22%,其应力呈下降趋势;鉴于桥梁常处于温-荷耦合状态下工作,温-荷耦合作用会减少铺装层最不利应力对纵坡的敏感性,且两者耦合作用有利于铺装层受力,故推荐文中曲线桥最佳纵坡坡度为6.22%。

The mechanical behavior of asphalt pavement on the deck of small radius curved bridge deck will be affected by the longitudinal slope size of the route. Taking an ultra-high curved bridge in large temperature difference area as an example, considering the viscoelastic properties of asphalt pavement, the stress conditions under different load conditions such as temperature, dynamic load and temperature load coupling are calculated respectively, and the influence of longitudinal slopes on the stress of bridge deck pavement are analyzed under different working conditions. In the analysis, the longitudinal gradient is taken as 4.22%, 5.22%, 6.22% and 7.22% respectively. The results show that the pavement surface is more prone to tensile failure when the temperature field or dynamic load acts alone, and different longitudinal slopes have a significant impact on the stress of σ. Dynamic load acting alone or temperature load coupling has higher requirements on the shear capacity of the lower layer of pavement. In particular, when the temperature load coupling is used, the stress of pavement surface generally increases with the increase of longitudinal slope, while for the lower layer of pavement, when the longitudinal slope is more than 6.22%, the stress decreases. Since the bridge often works under the temperature load coupling state, the temperature load coupling will reduce the sensitivity of the most unfavorable stress of the pavement to the longitudinal slope, and the coupling effect of the two will be conducive to the stress of the pavement. Therefore, it is recommended that the optimal longitudinal slope gradient of the curved bridge in the paper is 6.22%.